Microstructures and Properties of As-Cast Al2.7CrFeMnV, Al2.7CrFeTiV, Al2.7CrMnTiV High Entropy Alloys

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2024-12, Vol.55 (12), p.4796-4808
• Main Authors: Callahan, Patrick G., Beaudry, David, Michi, Richard, Zhou, Ryan, Stewart, Colin A., Knipling, Keith E.
• Format: Article
• Language: English
• Subjects: 3rd World Congress on High Entropy Alloys; Alloys; Aspect ratio; Characterization and Evaluation of Materials; Chemistry and Materials Science; Diamond pyramid hardness; Electric arc melting; Electron backscatter diffraction; High entropy alloys; Intermetallic phases; Lamellar structure; Laves phase; Materials Science; Metallic Materials; Microstructure; Nanotechnology; Polycrystals; Precipitates; Predictions; Structural Materials; Surfaces and Interfaces; Thermodynamic models; Thermodynamics; Thin Films; Topical Collection: High Entropy Alloys
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-024-07559-6

A family of high entropy alloys rich in Al have been produced by arc-melting and their microstructures, predicted by thermodynamic modeling and observed experimentally, are reported along with the alloys’ density and Vickers microhardness. Alloy 1 ( Al 2.7 CrFeMnV) consisted of a polycrystalline single-phase BCC microstructure with relatively equiaxed grains. Alloy 2 ( Al 2.7 CrFeTiV) consisted of a polycrystalline BCC matrix containing G phase precipitates with complex dendritic shapes and a Laves phase with large aspect ratio lamellae. Alloy 3 ( Al 2.7 CrMnTiV) consisted of a BCC matrix containing lath-shaped AlTi L1 0 precipitates and regions with coherent cuboidal precipitates having an ordered BCC structure. This ordered BCC phase was not predicted by equilibrium thermodynamic calculations but a B2 phase was expected using a metastable prediction. The regions of Alloy 3 containing the ordered BCC cuboids showed evidence of enhanced Vickers microhardness. The alloys were characterized in the as-cast state by several techniques, including scanning and transmission electron microscopy, X-ray diffraction, atom-probe tomography, and electron backscatter diffraction, and these results were used to validate the thermodynamic predictions by Thermo-Calc.